Brock Lesnar, John Cena, Roman Reigns and Shinsuke Nakamura set to feature at bumper event.

Part of the SummerSlam 2017 poster featuring Brock Lesnar, John Cena and others.WWE

WWE is firmly on the road to SummerSlam 2017, with just weeks to go before Raw and Smackdown come together for a huge night of wrestling action on 20 August at the Barclays Center in Brooklyn, New York.

It's one of WWE's biggest annual events – behind only Wrestlemania and arguably the Royal Rumble – and is expected to be a bumper, four-hour show like last year's event, where Brock Lesnar brutally and bloodily took out Randy Orton.

Lesnar will once again headline the show in one of the matches so far confirmed, but what other bouts will take place? Here are all the matches, booked or rumoured, so far.

Confirmed matches

Roman Reigns and Brock Lesnar are the only two men to defeat The Undertaker at Wrestlemania. After Reigns retired The Deadman earlier this year, he called out Brock, leading many to suspect the pair would face off again, one on one, for the first time since they main-evented Wrestlemania 31.

Clearly, that's not the case at SummerSlam. The pair will indeed clash, but Raw's breakout star of 2017 Braun Strowman and Samoa Joe, who faced Lesnar at the Great Balls of Fire event last month, will also be in contention.

Lesnar reportedly liked working with Joe, and Strowman has become one of the most popular characters in the company thanks to his brutal feud with Reigns this year.

WWE ChampionshipJinder Mahal (c) vs. Shinsuke Nakamura

Jinder Mahal was a jobber until just a few months ago, when an unexpected push led to a shock title win against Randy Orton. Having captured the title at Backlash in May, Mahal has amassed a crew of faces that have aided him in victory.

The Bollywood Boys and, at Battleground, a returning Great Khali helped Mahal retain against Orton, but it all seemed to be setting Mahal up for a run-in with all-American goody-two-shoes John Cena in an old fashioned, xenophobia-drenched wrestling feud between an American hero and the dirty foreigner.

Not quite. When Cena took on Shinsuke Nakamura last night (1 August) to earn the number one contender spot, it was the latter who surprisingly won the match on Smackdown and will now take on Mahal.

Raw Women's ChampionshipAlexa Bliss (c) vs. Bayley

Alexa Bliss is a genuine star, who won the women's championship not long after joining Raw following Wrestlemania. She ploughed through Bayley and seemed to be moving on to a feud with Sasha Banks. When Sasha defeated Bliss by countout last month, a rematch seemed inevitable – but instead Bayley is taking on Bliss once more.

Smackdown Women's ChampionshipNaomi (c) vs. Natalya

Naomi is the only face champion in the company at the moment, and that's been the case for a while. Natalya became number one contender unexpectedly after defeating Charlotte Flair, Becky Lynch, Lana and Tamina in a five-way match on Smackdown.

WWE Cruiserweight ChampionshipNeville (c) vs. Akira Tozawa

Tozawa defeated Ariya Daivari on Cruiserweight show 205 Live to become number one contender to Neville's title.

Randy Orton vs Rusev

The pair had a confrontation on Smackdown, a match was made. It was super simple really.